1. Field of the Invention
The present invention relates to a video signal processing apparatus and, more particularly, relates to a video signal processing apparatus for superimposing an anti-piracy signal (pilot signal) on a video signal, thereby preventing a video signal from being illegally dubbed, and a video signal processing apparatus for detecting an anti-piracy signal superimposed on a reproduced video signal, thereby prohibiting a video signal from being recorded.
2. Description of the Prior Art
To prohibit a video signal from being illegally dubbed, in a home-use VTR or the like, it is proposed that an anti-piracy signal (pilot signal) for prohibiting the video signal from being recorded is interposed to a synchronous signal portion.
However, in the above mentioned technique for interposing the anti-piracy signal to the synchronous signal portion, if the synchronous signal is replaced, the anti-piracy signal is also readily removed.
As another example of techniques for preventing a video signal from being illegally dubbed, a technique for superimposing on the video signal the anti-piracy signal at a high frequency out of the video signal band has been proposed. In this technique, since the anti-piracy signal is present out of the frequency band of the video signal, an image reproduced by a monitor unit is not disadvantageously deteriorated. However, in this technique, by a low pass filter in a simple circuit construction, the anti-piracy signal is readily removed. Thus, this technique does not satisfactorily prevent the video signal from being illegally dubbed.
Although other examples of techniques for preventing the video signal from being illegally dubbed have been known, an effective technique for preventing the video signal from being illegally dubbed without deterioration of the reproduced image has not been yet accomplished.